1. Field of the Invention
The present invention relates to a display module. More particularly, the present invention relates to a dual display module having a lower manufacturing cost and a better yield.
2. Description of Related Art
In this information-based society, our dependence on portable electronic products increases every day. Electronic products such as mobile phones, notebook computers, personal digital assistants (PDA) can be seen everywhere. As electronic technologies continue to progress, many types of multi-functional and personalized portable electronic products have been developed. For example, many types of mobile phones can be found in the market. Aside from the vertical type of mobile phones with an operating interface (keypad) on the same side as the display screen, other types of mobile phones include the one whose operating interface (keypad) and the display screen can be folded together. In general, the foldable type of the mobile phones has a larger display area and occupies a smaller space than a conventional vertical type phone. Recently, a foldable mobile phone with dual display screens is out in the market. Besides the main display screen, a smaller secondary display screen is set up on the surface of the front panel backing on the main display screen. The secondary display screen mainly serves to indicate time or incoming calls.
FIGS. 1A and 1B are schematic views showing the front and the back of a dual display module of a conventional mobile phone. The dual display module 100 comprises a first display panel 110, a second display panel 120, a first circuit board 130 and a second circuit board 140. Furthermore, the first display panel 110 has a size larger than the second display panel 120. The first circuit board 130 has a first surface 132 and a second surface 134. The first display panel 110 is set up on the first surface 132 of the first circuit board 130 and connected to the first circuit board 130 through a flexible circuit board 150. One end of the flexible circuit board is connected to the peripheral circuit of the first display panel 110. The other end of the flexible circuit board wraps around the side of the first circuit board 130 and presses against a first connection interface 134a on the second surface 134 of the first circuit board 130 to form a bond by anisotropic conductive paste (ACP).
As shown in FIG. 1B, the second display panel 120 is set up on the second surface 134 of the first circuit board 130 and electrically connected to the second connection interface 134b of the first circuit board 130 through the second circuit board 140. The second circuit board 140 is a flexible circuit board and electrically connected with the first circuit board 130 in a pressing manner by anisotropic conductive paste. In the aforementioned process, the first display panel 110 and the first circuit board 130 are first pressed together. Similarly, the second display panel 120 and the second circuit board 140 are electrically connected by a press fit process. Finally, the first circuit board 130 and the second circuit board 140 are pressed together. In other words, altogether three separate pressing processes are required to fabricate the dual display module.
The second circuit board 140 and the first circuit board 130 can be electrically connected using some other methods too. Referring to FIG. 1C, a back view of another dual display module of a conventional mobile phone is shown. The second circuit board 140 is assembled to the first circuit board 130 through a connector 160. Hence, the fabrication of the dual display module 100 involved two press-fit processes and an assembly process only. Although assembly using a connector 160 costs more than connection in a direct press-fit manner, yet a single slot in the connector 160 may simultaneously link up with a plurality of leads. Hence, further expansion or alteration is permitted in the presence of the connector 160. In addition, the manner by assembling further aids subsequent product repair.
However, because the aforementioned dual display modules demands the first display panel and the second display panel assembled through the first circuit board and the second circuit board respectively, the production cost regardless whether a flexible circuit board or a connector is employed. Moreover, the conventional dual display module has to be assembled in at least three steps. When the number of processing steps is increased, not only fabrication time is prolonged but more assembling errors are also occur. Eventually, the productivity and assembling yield of the dual display module will drop.